1. Field of the Invention
The present invention relates generally to brake monitoring systems and arrangements for use in connection with an air brake arrangement, and in particular to an empty-load device feedback arrangement and an air brake arrangement for a train, railcar, railway vehicle, and similar vehicles, and preferably an electronically-controlled pneumatic air brake arrangement for a railway vehicle.
2. Description of the Related Art
As is known in the art, braking systems and arrangements are required for slowing and stopping vehicles, such as cars, trucks, trains, railcars, railway vehicles, and the like. With specific respect to trains and other railway vehicles, the braking system is normally in the form of a pneumatically-driven arrangement (or “air brake arrangement”) having mechanisms and components that interact with each railcar. A known air brake arrangement BA is illustrated in schematic form in FIG. 1.
With reference to FIG. 1, the operator of a train TR also has control over the braking arrangement BA through the use of an operator control valve CV. Through the movement of a handle associated with the control valve CV, the operator can adjust the amount of braking to be applied in the air brake arrangement BA. The higher the braking force selected, the faster the braking arrangement BA will attempt to slow and stop the train TR. Alternatively, and as discussed in more detail hereinafter, the air brake arrangement BA for each railcar may also be controlled by the operator from an on-board controller OBC that transmits data signals over a trainline TL (or cable extending between the locomotive and the railcars), which may be referred to as an electronically-controlled pneumatic (ECP) air brake arrangement. In addition, the on-board controller OBC may also be referred to as a head-end unit (HEU) when used in connection with an ECP-based braking system. Of course, the on-board controller OBC and head-end unit may be integrated as a single controller for use by the operator of the train TR.
In order to provide the appropriately compressed air to the system, and in certain conventional air brake applications, the air brake arrangement BA also includes a compressor C for providing compressed air to a main reservoir MR, which is in communication with the control valve CV. Further, an equalizing reservoir ER is also in communication with the control valve CV. Whether through the main reservoir MR or the equalizing reservoir ER, compressed air is supplied through the control valve CV to a brake pipe BP that extends along and is associated with each railcar. Each railcar includes an arrangement that allows an auxiliary reservoir AR to be charged with air via a valve V, as well as a braking assembly or unit BU, such as a brake cylinder BC, which is in communication with the valve V. The brake cylinder BC is operable to urge a brake shoe mechanism BS against a surface of the wheel W.
In operation, the brake pipe BP is continually charged to maintain a specific pressure, e.g., 90 psi, and each auxiliary reservoir AR and emergency reservoir ER (which may be combined into a single volume, or main reservoir) are similarly charged from the brake pipe BP. In order to brake the train TR, the operator actuates the control valve CV and removes air from the brake pipe BP, thereby reducing pressure to a lower level, e.g., 80 psi. The valve arrangement V quits charging the auxiliary reservoir AR and transfers air from the auxiliary reservoir AR to the brake cylinder BC. Normally using piston-operable arrangement, the brake cylinder BC urges the brake shoe mechanism BS against the wheel W. As discussed, in conventional, non-ECP air brake systems, the operator may adjust the level of braking using the control valve CV, since the amount of pressure removed from the brake pipe BP results in a specific pressure in the brake cylinder BC, which results in a specific application force of the brake shoe mechanism BS against the wheel W. Alternatively, in the ECP air brake arrangements, the brake commands are electronic over the ECP trainline TL to each railcar. Using the above-described air brake arrangement BA, the train can be slowed and/or stopped during operation and as it traverses the track.
In order to provide further control to the air brake arrangement BA, ECP brake arrangements can be used, such as in connection with certain railway vehicles and trains (e.g., freight trains and the like). As discussed, control signals can be transmitted from the on-board controller OBC, typically located in the cabin of the locomotive, to one or more of the railcars over the trainline TL. Each railcar is normally equipped with a local controller LC, which is used to monitor and/or control certain operating parameters in the air brake arrangement BA, such as the air reservoirs and/or the valve arrangement V. In this manner, the operator can broadcast brake commands to the railcars to ensure a smooth, efficient, and effective braking operation. This local controller LC typically includes the appropriate processor and components to monitor and/or control various components of the air brake arrangement BA.
With further reference to ECP-based air brake arrangements BA, such control facilitates effective train operation by permitting all railcars of the train TR to apply and release brakes at the same time, instead of being limited by the propagation delay of the above-discussed basic pneumatic control. Instead, using the ECP system, the operator may simply issue or set a “Train Brake Command” (TBC), which is transmitted to all of the railcars simultaneously. Still further, such an ECP system improves safety by alerting the operator about any error conditions, e.g., if a car detects that it is unable to apply brakes, if a car detects that the brakes are or have been over applied, and the like. In addition, the ECP system is typically configured to monitor brake pipe pressure, reservoir pressure, and upstream brake cylinder pressure at the railcar level.
As is known, the weight of a freight car can vary drastically, such that a loaded hopper car (FIG. 2(a)) may weigh 3-4 times the weight of an empty car (FIG. 2(b)). Accordingly, the amount of pressure in the brake cylinder BC needed to stop a loaded railcar is much higher than the pressure needed to stop an empty car. Accordingly, if the amount of pressure needed to stop a loaded car was applied to an empty car, the wheels W would skid, causing wheel W and track damage. Similarly, if the amount of pressure needed to stop an empty car was applied to a loaded or partially loaded car, the braking performance would be reduced, potentially to the point where the railcar may not stop at all (e.g., braking the car on a grade). In order to address this issue, and with continued reference to FIG. 1, conventional freight cars are normally equipped with an empty-load device EL. Such an empty-load device EL are configured to regulate the brake cylinder BC pressure when a car is empty. When a car is loaded, the empty-load device EL allows for full pressure (or full application) in and by the brake cylinder BC.
As is known, the empty-load device typically uses the height of the railcar body as the mechanical input to the regulator switch between “empty” and “loaded” settings. For example, the sensor arrangement may be in the form of a lever or arm that rotates or moves based upon the height of the car body with respect to the truck. In addition, it is noted that empty-load devices EL are available with different regulation amounts. For example, some empty-load devices EL may regulate the “downstream” pressure to 50% of the “upstream” pressure when an empty car is detected, while others may regulate the “downstream” pressure to some other percentage of “upstream” pressure, e.g., 60%, 40%, and the like.
There exists a need in the industry to ensure that the appropriate regulated pressure is being delivered by the brake cylinder (or other air-operable braking assembly). Further, there exists a need in the industry to detect the proper operation, failure, and/or need for maintenance of the empty-load device. There is also a need in the industry for the enhancement of the effective operation of existing and newly-installed empty-load devices on railcars and other vehicles having air-operable braking assemblies and air brake arrangements.